update device for libzmq3

zmq_device is no longer removed, and zmq_proxy is added.
So there is no longer a reason to roll our own zmq_device implementation.
default args for Device constructor
add proxydevice
fix missing QUEUE
Proxy devices
monitoredqueue inherits from proxy
remove conditional import of multiprocessing

safe since we depend on 2.6 now
add proxydevice to devices.__init__
check zmq version in ProxyDevice
basic test for zmq.proxy
rollback version check in ProxyBase

because MonitoredQueue inherits from ProxyBase
Merge pull request #289 from minrk/nodevice

update to current state of devices in libzmq

zmq.proxy is new version of zmq.device
remove reduntant custom zmq_device implementation